.calculator{
    padding: 100px 0 0 500px;
}
.calculator .screen{
    line-height: 70px;
    font-size: 1.5em;
    padding: 0 5px;
    height: 70px;
    width: 600px;
    border: 1px solid black;
}
.calculator .box .row{
    width: 600px;
    display: flex;
    display: -webkit-flex;
}
.calculator .box .row>div{
    font-size: 1.5em;
    height: 70px;
    text-align: center;
    line-height: 70px;
    background:#eaeaea;
    border-left: 1px solid black;
    border-bottom: 1px solid black;
    cursor: pointer;
}
.calculator .box .row>div:last-child{
    border-right: 1px solid black;
    background:#738fd8;
    color: white;
}
.calculator .box .row .cell-1{
    width: 50px;
    flex-grow: 1;
    -webkit-flex-grow: 1;
}
.calculator .box .row .cell-2{
    width: 100px;
    flex-grow:2;
    -webkit-flex-grow: 2;
}